Chris,
I bought my Thousand Oaks white light filter locally from here:
http://www.astroshop.com.au/products/solar-filters.asp
You just need to measure the outer diameter of where the filter will go (such as dew shield) and find the next size up, e.g. the diameter of my dew shield is 158 mm, so I had to get the 165 mm filter.
It comes with an adhesive felt liner to help give a snug fit, but I'm a bit safety obsessed so I always gaffe tape the filter on securely if I'm looking through an eyepiece
The Thousand Oaks one is nice because it adds a yellow-orange tinge to the sun, i.e. it looks "natural" rather than white/grey. Here's a pic that I shot with my SLR attached at prime focus (minimal post processing).
Cheers,
Dave